1. Field of the Invention
The present invention relates to a capacitance sensing apparatus and a touch screen apparatus.
2. Description of the Related Art
A touch sensing device such as a touch screen, a touch pad, or the like is an input device mounted on a display apparatus, allowing a user to intuitively input data. Recently, touch sensing devices have been widely used in various electronic devices such as portable phones, personal digital assistants (PDA), navigation devices, and the like. In particular, recently, as demand for smart phones has increased, a touch screen has been increasingly used as a touch sensing device for providing various input methods within a limited form factor.
Touch screens used in portable devices are classified as resistive-type touch screens and capacitance-type touch screens, according to a method of sensing a touch input. Among these, capacitance-type touch screens have relatively longer lifetimes and are advantageous in allowing for various input methods and easily recognizing various gestures, and thus have increasingly been used. In particular, since a multi-touch interface may be easily implemented in capacitance-type touch screens, as compared with resistive-type touch screens, capacitance-type touch screens are widely used in devices such as smart phones.
Capacitance-type touch screens include a plurality of electrodes having a predetermined pattern, and a plurality of nodes, in which a change in capacitance is generated by a touch input, are defined by the plurality of electrodes. In a plurality of nodes distributed on a two-dimensional (2D) plane, a change in self-capacitance or mutual-capacitance is generated by a touch input, and a weighted average calculation method or the like is applied to the change in capacitance generated in the nodes so as to obtain coordinates of the touch input. In order to obtain accurate coordinates of the touch input, technologies for accurately detecting a change in capacitance generated by the touch input are required. However, when electrical noise is generated in a wireless communications module, a display apparatus, and the like, electric noise may impede accuracy of sensing a change in capacitance.